1st year Chemistry Chapter 8 Introduction TO Chemical kinetics Question an Answers
Short and Simple Question an Answer
Q.1: Define activation energy and activated complex?
Ans: Activation energy is the maximum amount of energy more than the average energy, which is just sufficient convert reactants into products.
Activation complex is the collection of molecules of reactions as the time of collision having greater energy than the reactions and products. At this stage old bonds become
weak and the possibilities for the new bonds are then.
Q.2: What is temperature coefficient of a reaction?
Ans: It has been observed that by increasing the temperature of a reaction by 10 K. the rate constant doubles. This is called temperature coefficient of a reaction. Bagsp
Q.3: What is the effect of temperature on tire activation energy of a reaction?
Ans: Activation energy of the chemical reactions is a constant parameter and does not depend upon the temperature. Any how, by increasing the temperature greater number of molecules get a chance to cross the activation energy barrier.
Q.4: The rate of a chemical reaction is an ever changing parameter under the given conditions?
Ans: When the reaction progresses, the reaction is very fast at the beginning, slow somewhere in the middle and very very slow at the end. The reason is that rate depends upon the concentration according to the law of mass action. The Concentrations decreases every moment, so rate decreases every moment.
Q.5: The reaction rate decreases every moment but the rate constant ‘K’ of the reaction is a constant quantity, under the given conditions? Justify it?
Ans: Rate constant is the rate of chemical reaction when the concentration of reactants are unity.
The concentration of A and B decreases with the passage of time, so the rate decreases, but the rate constant “K” remains the same for the reactions throughout, its progress under the given conditions.
Q.6: When the reaction become zero order?
Ans: Those chemical reactions whose rates are independent of the concentrations of reactants and are mostly influenced by a suitable catalyst, or light are zero order reaction. Thus units for rate constant for such reactions are equal to the units of rates of reactions.
Q.7: The radioactive decay is always a first order reaction? How?
Ans: Radioactive substance have a single species at a moment whose nucleus is being broken up without the help of any external agency. So only one reactant is present and it allows the first order mechanism.
Q.8: What type of information is obtained for the order of reaction from half life period of that reactions?
Ans: Half life period depends upon the initial concentration of reactants. Actually, half life period is inversely proportional to the initial concentration of reactants raised to the power one less than the order of reaction. So from the initial concentration and half life period order of reactions can be calculated.
Q.9: The reaction happened due to collisions among the molecules, but all the collisions are not fruitful?
Ans: In order to do the chemical reaction, a minimum amount of energy, more than the average energy is required. Hence only those collisions will prove to be fruitful whose energies are more than or equal to the energy of activation. Moreover, proper orientation is also required. Due to these facts the reactions do not happen in a single moment, but they takes some times.
Q.10: How the energy activation can be calculated from the Arrhenius plots?
Ans: When a graph is plotted between inverse of temperature on x-axis and log k on the y- axis, then a straight line with the negative slope is obtained. The slope of this straight line gives us the energy of activation.